Hammermills of the type contemplated herein are used to break up metal car bodies. These mills, also known as shredders, are fragmentation machines, which meet their objective by impact.
Hammermills possess impact devices that oscillate on the ends of radially directed rotor arms and generally include hammers, taking on a flat position when sufficient torsion speed of the rotor is applied. A well-known configuration features hammers suspended between disks that are affixed to the rotor shaft. Another configuration features a hammer supported between adjacent rotor arms. The hammers are located on a shaft situated parallel to the main shaft, the radial position of this shaft runs through all of the rotor arms and hammers. The number of shafts is equal to the number of the rotor arms to support the hammers.
The hammers are subjected to extraordinary wear and tear and are replaced by new hammers after only a number of days of service. After initial use, some may be reused after having been shifted 180.degree.. Yet, the production period of such a hammermill is relatively short. The free standing ends of the rotor arms in this type of hammermill are also subject to wear. Attempts have been made to fit the rotor arm ends with protective caps that are also attached to the shaft that supports the hammers. Finally, it is worth noting that the frequent exchange of hammers and protective caps requires the disassembly of the full length of the supporting rod.
In the hammermills disclosed and described in U.S. Pat. No. 4,313,575 and U.S. Pat. No. 3,844,494 the supporting rods for the protective caps and the supporting rod for the hammers are situated behind each other in circumferential direction. Thus, the front edges of the rotor arms, especially exposed to wear, are protected by the caps. Even though these configurations do not require the dismantling of the hammers in order to change the protective caps, a costly supplemental arrangement is required to secure the caps to the rotor arms.